Welcome to this site. This website will teach a few of the basics of sailing and what Physical forces are involved in sailing.
The basics of a sail boat:
To start off you should know a little about a sail boat, sails and some terminology. If you have experience in sailing you could go on to the next page.

The Hull of the boat is the frame which keeps the boat and its crew floating in the water. The mast is the tall pole that sits vertically near the center of the hull, the mast is what the sails are attached to to keep them suspended and straight. The boom is a large pole attached to the bottom part of the mast which is able to rotate up, down and side to side. The sails attach to the boom and the mast then the person controlling the main sail moves the boom around to change the direction and tension in the mainsail.

The rudder is atached to the rear of the boat and is what essencially steers the boat (note that the rudder alone will not steer the boat exactly where you want to go in a sailboat unlike other motorboats).

The most difficult part of a sail boat for most beginners to understand is the keel or centerboard. The keel of the boat does many things, it acts as a pivital point for sharp turns and "jibbing", it helps keep the boat upright by lowering the center of gravity of the boat, it works to keep the boat moving in a line of motion close to that of the direction that the boat is facing. This is because the boat is usually being pushed heavily to the side by the wind. And the keel also works to pull the boat into the direction of the wind the same way the sails do. This is a concept that I will discuss later on.
The Sails:
The sails of the boat are what provide the forward thrust. There can be several sails but in every sail boat there is a main sail. That is the sail which is attached to the mast and is usually the tallest sail on the boat, it is controlled by the boom and has several attachments used for slight adjustments to get the most effeciency. There is usually a "jib", a smaller sail in the front of the boat attached to a guy wire which reaches about %75 of the height of the mast or main sail. The jib provides additional forward force but is just as usefull in providing manuverability in low speed or low wind situations or moving out of a docks area. In this site I will refer only to sailboats with a standard mainsail and jib, as in the picture to the right.

The main parts of the sails that are important to remember are the head, the tack, the foot, the leech and the clew. These are in the following picture to the right.
Notice the shape of the sails, both are triangular however the jib seems to be facing an opposite direction, yet they both have the same properties and work in the very same way. This is because the clew of both sails are the only part that is really adjusted while sailing.
Next: How sails push the boat in the same direction